The present invention relates to a drag washer used for a drag mechanism of a fishing reel and to a fishing reel using the same.
In general, a drag mechanism of a fishing reel is given a setting of a braking force so that when a tensile force in excess of a predetermined value is exerted on a fishing line, the drag mechanism is made to slip to allow the fishing line to be reeled out in response to pull of hooked fish, so as to prevent the fishing line from being break. The drag washers that are generally used as braking friction plates in the drag mechanism include, for example, asbestos-phenol-resin molded material, flammable woven fabric greased or impregnated with oil grease, and carbon-fiber woven fabric impregnated with resin and cured.
These drag washers have the problems, however, that the friction resistance is subject to change under environmental changes, such as change in friction resistance caused by entrained seawater, change in friction resistance caused by frictional heat, and change in friction resistance resulting from durability in thickness direction against tightening force.
To eliminate these drawbacks of the conventional drag washers, graphite drag washers have been developed recently. The graphite drag washers have the advantages of being hardly subject to change in friction resistance under environmental changes and providing the excellent drag force for an extended time period.
However, in the producing process of the graphite drag washers, it is required that the drag washers are cut out into any desired size from some degree of size of graphite block by machining.
This causes increased costs in manufacturing the fishing reel using the graphite drag washers, leading to the disadvantage that the use of the graphite drag washers are limited to some high-grade goods. In addition, when used for general fishing, the graphite drag washers can produce excellent drag force and provide comfortable operation for an extended time period.
However, when the graphite drag washers are used to a large-sized fishing reel for marlin and large-sized fish, whose drag mechanism is given a setting of braking force of a relatively large value, there is the possibility that when a large braking force is exerted on the drag washers, the graphite drag washers may be cracked due to its own fragility that is one of the disadvantages of the graphite material.
It is the object of the present invention to provide a drag washer for a fishing reel that can provide a drag force equal to or more than that of the graphite drag washer for an extended time period, can be produced at reduced costs and without difficulty and is applicable to a variety of fishing reels for a variety of fish ranging from small-sized fish to large-sized fish.
The inventors have focused attention on an expanded graphite sheet having an excellent sliding property equivalent to that of the graphite material and have pursued their studies thereon with their whole heart. The conventional expanded graphite sheet has an excellent sliding property, but on the other hand, it lacks some required properties for the drag washer of fishing reel, such as strength and hardness. Due to this, it was practically infeasible to use the expanded graphite sheet for the drag washer of fishing reel.
The inventors have found that enhanced hardness can be produced by adding heat-resistant reinforcing fiber, such as fiber pulp, used as reinforcing material to the expanded graphite and then binding them by use of a heat-resistant binder such as thermosetting resin. Further, they have found the proportion in which three components, namely, expanded graphite, heat-resistant reinforcing fiber and heat-resistant binder, are mixed to produce a sheet having the required strength and sliding properties for the drag washer of fishing reel, then bringing the invention to completion.
A fishing reel""s drag washer of the present invention is formed from a sheet comprising a mixture of expanded graphite and heat-resistant reinforcing fiber as is solidified by a heat-resistant binder. It is preferable that the sheet has a thickness of 0.7-1.2 mm and a bulk density of 0.8-1.2 g/cm3. Also, the sheet is produced in such a process that 40-80 mass % of expanded graphite, 5-25 mass % of heat-resistant reinforcing fiber and 10-40 mass % of heat-resistant binder are mixed, followed by heat-treatment to cure the heat-resistant binder.
The expanded graphite used for the fishing reel""s drag washer of the present invention is produced as follows. For example, flake graphite is subjected to acid treatment by using sulfuric acid and oxidizing agent to thereby produce acidized graphite, first, and then heated rapidly to approximately 1,000xc2x0 C. so as to be expanded 100-300 times. Thereafter, the expanded graphite is ground in powdery form by using a granulator. Then, after the expanded graphite is formed into a felt form or a sheet form having a bulk density of 0.05-1.5 g/cm3, the expanded graphite of felt form or sheet form is further ground in powdery form by using any proper high-speed mill type of grinder. Preferably, the powders of either of the felt and sheet have a bulk density of 0.05-1.5 g/cm3 and a mean particle size of 150-250 xcexcm. The expanded graphite ground into powdery form by the granulating method is easily delaminated, so that it is uniformly mixed with the heat-resistant reinforcing material and the heat-resistant binder with ease. The expanded graphite obtained when the felt of a bulk density of less than 0.05 g/cm3 is ground becomes so bulky that it is hard to deal with. On the other hand, the expanded graphite obtained when the sheet of a bulk density of more than 1.5 g/cm3 is ground is formed in the granular form, so that the characteristics of the expanded graphite itself are impaired.
Preferably, the heat-resistant reinforcing fiber is in a pulp form and have a large specific surface area, in terms of heat resistance as well as reinforcement of the expanded graphite powder. The fibers that may be used include inorganic fiber, organic fiber and metal fiber. Practically, the organic fiber that can take a relatively large specific surface area is preferably used. To be more specific, aramid fiber pulps of para-series or meta-series may be used. Also, infusible cellulose pulps may be used, though there is a limit to use.
The aramid fiber pulp of para-series used as the heat-resistant reinforcing fiber mentioned above is preferably 3.0 m2/g or more in specific surface area, or further preferably 5-20 m2/g. The fiber length of 0.9-2.0 mm affords good dispersibility and high filler retention of 50-70%. The specific surface area of less than 3.0 m2/g is not good enough to provide the reinforcing effect of the expanded graphite and as a result, the strength of the sheet obtained is reduced.
Thermosetting resins are preferably used as the heat-resistant binder for bonding the expanded graphite and the heat-resistant reinforcing fiber. Particularly preferable are phenol resin, polyester resin, and epoxy resin. Among others, fine-grained phenol resin having a mean molecular weight of not less than 5,000 and a mean particle size of not more than 20 xcexcm which affords excellent sliding properties is of preferable. This thermosetting resin is easily soluble in solvent and is able to be uniformly dispersed in between the expanded graphite powders and the fiber pulps.
For the purpose of enhancing the sliding properties, 4-5 mass % of molybdenum disulfide powder may be added as sliding material, if required. This enables the control of the sliding properties of the drag washer.
The sheet used for the fishing reel""s drag washer of the present invention is produced by the respective materials cited above being mixed and then solidified. The respective materials are preferably mixed in a mixing proportion of 40-80 mass %, or preferably 50-70 mass %, of expanded graphite, 5-25 mass %, or preferably 10-20 mass %, of heat-resistant reinforcing fiber and 10-40 mass %, or preferably 20-30 mass %, of heat-resistant binder. Less than 40 mass % of expanded graphite would not produce the properties of the expanded graphite, while on the other hand, more than 80 mass % of expanded graphite would not develop the satisfactory strength. Less than 5 mass % of heat-resistant reinforcing fiber would not produce satisfactory heat resistance, while on the other hand, more than 25 mass % of heat-resistant reinforcing fiber would reduce dispersibility. Less than 10 mass % of heat-resistant binder would not develop the satisfactory slidability, while on the other hand, more than 40 mass % of heat-resistant binder would increase hardness and impair the properties of the expanded graphite. If required, 4-5 mass % of molybdenum disulfide powder may be added as sliding material.
The sheet used for the fishing reel""s drag washer is made from the materials mixed in the mixing proportion mentioned above. The producing method is classified broadly into the dry process and the wet process. In the following, the dry process and the wet process will be described separately.
First, the producing method using the dry process will be described below.
The heat-resistant binder is previously dissolved in solvent such as methanol. Then, the heat resistant binder thus prepared, the heat-resistant reinforcing fiber and expanded graphite as previously mentioned are uniformly dispersed and mixed in any proper mixing machine such as a kneader. Then, the raw material thus mixed is fed to a calendar roll, that is an apparatus for producing a joint sheet and the like, and is rolled spread to uniform thickness to produce the sheet. When the raw material is wound around the heated calendar roll, the solvent in which the heat-resistant binder is dissolved is evaporated and also the heat-resistant binder is melted and solidified, to thereby produce a desired sheet.
Second, the producing method using the wet process will be described below.
In the wet process, the expanded graphite molded in felt form of a bulk density of 0.05-1.5 g/cm3 is granulated by using a large amount of water and a mixer of hydro-pulper type and the like, though the powdery expanded graphite may be used. The heat-resistant reinforcing fiber is added thereto and is uniformly dispersed. This is passed through a refining mill to adjust the mean particle size of the expanded graphite to 180-230 xcexcm. If the bulk density of the felt obtained at that time is less than 0.05 g/cm3, the expanded gas in the void of the expanded graphite particles is not removed with ease and, as a result of this, the raw material is put into a floating state even when agitated and ground in water. On the other hand, if the bulk density of the felt obtained is more than 1.5 g/cm3, the ground raw material is granulated and, as a result of this, the strength of the sheet is reduced. Then, the heat-resistant binder is added and is uniformly dispersed. When the heat-resistant binder is dispersed, anionic dispersing agent or NBR latex is preferably added, in order to provide improved dispersibility. Thereafter, aqueous solution of cationic flocculating agent is added to fix the heat-resistant binder completely. Preferably, the concentration of the raw material comprising expanded graphite, heat-resistant reinforcing fiber and heat-resistant binder dissolved in the mixed solution is 1.0-2.0%.
A prescribed amount of mixed solution, in which the raw material concentration of 1.0-2.0% comprising expanded graphite, heat-resistant reinforcing fiber and heat-resistant binder is dissolved, is poured into a tank having a wire cloth of a given size. Then, the mixed solution is diluted by an equal amount of water and is dispersed uniformly. Thereafter, it is dehydrated (dehydration process) to obtain a sheet of water content of 50-60%. Then, with the sheet sandwiched between felts, the sheet was compressed by a press, for further dehydration. Then, the sheet is put in an oven of 100-120xc2x0 C. and dried therein. Thereafter, the sheet is passed through the calendar roll and heat-treated at 150-250xc2x0 C. for 0.5-1.0 hour to cure the heat-resistant binder, so that the sheet is adjusted to 0.7-1.2 mm, or preferably 0.7-1.0 mm, in thickness and 0.8-1.2 g/cm3 or preferably 0.9-1.1 g/cm3, in bulk density. The sheet of a thickness of less than 0.7 mm would not develop satisfactory strength for the drag washer. On the other hand, the sheet of a thickness of more than 1.2 mm would provide an increased friction resistance, resulting in providing inadequate drag force. The sheet of a bulk density of less than 0.8 g/cm3 would not develop satisfactory strength for the drag washer, as in the case of the thickness being reduced. On the other hand, the sheet of a bulk density of more than 1.2 g/cm3 would undergo a lot of changes in coefficient of dynamic friction and the coefficient of friction would then be apt to increase with time and, as a result of this, the sheet could not be practically used as the drag washer for an extended time period. As a result of the bulk density being within this specific range, adequate voids are produced. When the drag washer formed from the sheet having this specific bulk density is fitted to a fishing reel, there is provided the advantage that when lubricant such as grease is applied to the drag washer, the lubricant is charged in the voids and, as a result of this, reduction in lubrication caused by permeation of water and sea water in the drag is prevented. It is to be noted that this process is suitable for production of a single piece of sheet.
In the case of producing a continuous sheet, a prescribed amount of mixed solution, in which the raw material concentration of 1.0-2.0% comprising the expanded graphite, the heat-resistant reinforcing fiber and the heat-resistant binder is dissolved, is poured into the tank. Then, the mixed solution is diluted by the equal amount of water and is dispersed uniformly. Thereafter, the suspension is passed through two double-wire screens and is dehydrated to obtain a sheet of water content of approximately 70%. Further, the obtained sheet is passed through a felt press, so as to be dehydrated to a water content of approximately 50% and, thereafter, it is passed through a multicylinder drier to be dried. Then, the sheet is passed through the calendar roll of room temperature and is so adjusted as to have a thickness of 0.7-1.2 mm, or preferably 0.7-1.0 mm, and a bulk density of 0.8-1.2 g/cm3 or preferably 0.9-1.1 g/cm3. When the sheet is passed through the calendar roll of room temperature, rather than through the heated calendar roll, increased surface roughness is provided, leading to enhancement of drag force. Thereafter, it is heat-treated in a drier of 150-250xc2x0 C. for 0.5-1.0 hour to cure the heat-resistant binder and solidified.
The sheet thus produced is formed into any desirable size and shape by punching, to form the drag washers applicable to all types of fishing reels for a variety of fish ranging from a small-sized fish fishing reel to a large-sized fish. Also, the sheet thus produced enables the fishing reel""s drag washer to be produced at reduced costs, as compared with the conventional material used for the drag washer.